Field of the Invention
The invention relates to an adjustment module and an optical device, and more particularly, to a projection lens adjustment module and a projector.
Description of Related Art
A projector is a display device capable of enlarging and projecting frames into a projection surface. The imaging principle of projectors is to convert an illumination beam generated by a light source into an image beam via a light valve, and then to project the image beam onto a projection surface (such as a screen or a wall) through a projection lens so as to form an image. With advancement in projection techniques and reduction in manufacturing cost of projection devices, applications of projection devices have been gradually expanded from commercial use to household use.
In general, the projector provides a focus ring for a user to adjust the focus of a projection lens. Conventionally, the focus ring is disposed to protrude from the top of the projector, in order for the user to focus the projection lens at the top of the projector in a manual operation manner. Under such configuration with the focus ring, if the projector is designed to have the projection beam transmitting towards the top of the projector via the reflection of a reflective mirror after being projected out of the projection lens, the projection beam will easily be blocked as the user operates the focus ring resulting in the incomplete of projection frames. As such, the accuracy and convenience of focusing are both affected, such as a low-f-number projector. In addition, some conventional projectors are configured to dispose the focus ring at the bottom of the projector. Although such design may prevent the projection beam being blocked as the user operates the focus ring, the projector requires to be lifted from a table surface in order to operate the focus ring. By this way, the projection frames are shifted, which may not be facilitated to adjust the focal length of the projection lens.
China Patent Publication no. CN 101261359 discloses a projector, which allows the user to operate the knob member in an up-and-down moving manner so as to adjust a focusing condition of the projection lens unit. China Patent Publication no. CN 2804888Y discloses a lens module structure, which employs the step motor to drive the rack bar to move so as to drive the rotation seat to adjust the focal length of the projection lens. China Patent Publication no. CN 101025465A discloses a projector, which the turn table thereof is disposed at the top of the projector where the first gear part on the turn table is engaged with the second gear part on the lens barrel, such that the user is capable of rotating the turn table to drive the lens barrel to operate, so as to adjust the focus of the projection lens.
The information disclosed in this BACKGROUND section is only for enhancement of understanding of the BACKGROUND of the described technology and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Further, the information disclosed in the BACKGROUND section does not mean that one or more problems to be resolved by one or more embodiments of the invention was acknowledged by a person of ordinary skill in the art.